| Fuel filters - before of after electric pump? [message #80544] |
Wed, 14 April 2010 13:08  |
Mike O'Connell
Messages: 53
Registered: November 2008
Location: Deerfield MA
Karma: 0
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There seems to be diverging opinions as to where one should install a fuel filter when using an electric pump by the tanks.
I see that most here and on the photo site put the filter before the pump, yet most advice online elsewhere would put it after the pump.
The reason for after seems to be that fuel pumps (especially electric) are more affected by restriction on the suction side than the pressure side. The thinking seems to be that additional negative pressure on the suction side could cause a cavitation problem, which is what the whole electric fuel pump implementation is supposed to be solving. Additionally if the electric pump buys the farm particles would be trapped by the filter.
Is this reasoning sound or are there factors with the GMC that I'm overlooking here?
Mike O'Connell
Deerfield, MA
'75 Eleganza
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| Re: Fuel filters - before of after electric pump? [message #80547 is a reply to message #80544] |
Wed, 14 April 2010 13:20  |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Senior Member |
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Mike,
I don't have an electric pump, but have been looking at them online. I noticed in the Summit catalog that it appears that a lot of the rotary (vane) type pumps suggest a 10 micron filter before the pump. Some of the other types (diaphragm or plunger) don't. So, I'm guessing the vane pumps are pretty sensitive to dirt, which would make sense. Not sure what the micron rating of the stock fuel socks are. I've replaced mine and I know they are in place and good, but a lot of people blow them off with air.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: Fuel filters - before of after electric pump? [message #80548 is a reply to message #80544] |
Wed, 14 April 2010 13:23 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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The Carter 4070 suggests the filter be before the pump. If there isn't one there, they will not warranty the pump. That said, I have never heard of anyone taking one in for warranty.
I have two inline (one for each tank) before the pump and the tank selector valve. If one were to plug up I simply switch tanks and continue on my way. I have never had a filter plug up.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Fuel filters - before of after electric pump? [message #80557 is a reply to message #80544] |
Wed, 14 April 2010 14:31 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Mike,
All pump installation that I have seen have shown a filter before the
the pump and some say no filter, no warrantee.
I run 2 filters in my all electric fuel system. The first is just
before the p4070 and the second is in the line to the carb where my
manual fuel pump used to be located at. I change them twice a year
and I run no filter in the carb.
J.R. Wright
GMC GreatLaker
TZE Zone Restorations
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan
On Apr 14, 2010, at 2:08 PM, Mike O'Connell wrote:
>
>
> There seems to be diverging opinions as to where one should install
> a fuel filter when using an electric pump by the tanks.
> I see that most here and on the photo site put the filter before the
> pump, yet most advice online elsewhere would put it after the pump.
> The reason for after seems to be that fuel pumps (especially
> electric) are more affected by restriction on the suction side than
> the pressure side. The thinking seems to be that additional negative
> pressure on the suction side could cause a cavitation problem, which
> is what the whole electric fuel pump implementation is supposed to
> be solving. Additionally if the electric pump buys the farm
> particles would be trapped by the filter.
>
> Is this reasoning sound or are there factors with the GMC that I'm
> overlooking here?
> --
> Mike O'Connell
> Deerfield, MA
> '75 Eleganza
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Fuel filters - before of after electric pump? [message #80561 is a reply to message #80547] |
Wed, 14 April 2010 15:15 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Craig,
Here's a picture of the strainer on the fuel tank pickup out of Jim K's
catalog. When it opens the curser is a "+" sign inside a circle click and
the picture gets HUGE!
http://www.appliedgmc.com/products/full/773.jpg
Jim can you tell us what the micron size it is?
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Craig Lechowicz
Sent: Thursday, 15 April 2010 4:20 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Fuel filters - before of after electric pump?
Mike,
I don't have an electric pump, but have been looking at them online. I
noticed in the Summit catalog that it appears that a lot of the rotary
(vane) type pumps suggest a 10 micron filter before the pump. Some of the
other types (diaphragm or plunger) don't. So, I'm guessing the vane pumps
are pretty sensitive to dirt, which would make sense. Not sure what the
micron rating of the stock fuel socks are. I've replaced mine and I know
they are in place and good, but a lot of people blow them off with air.
--
Craig Lechowicz
'77 Kingsley, Waterford, MI
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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